Time-domain Differential Protection Based on Operating and Restraining Trajectory Indices for Lines Connecting Battery Storage Energy Stations

Battery energy storage stations(BESSs)pose sever-al challenges for both phasor-based differential protection and the newly-proposed time-domain differential protection.These challenges include low sensitivity and even rejection.Besides,the negative impact of various nonideal conditions,including current transformer(CT)saturation,errors,and outliers,on the security of differential protection remains an important problem.Motivated by the aforementioned issues,this study accounts for the trajectory distribution discrepancy on Cartesian plane under various conditions and proposes a time-domain differential protection method.In this paper,the trajectory formed by operating and restraining current samples is devel-oped.Subsequently,after considering different operating states,the fault severity levels,and nonideal conditions,the variances in trajectory distribution between internal and external faults are extensively analyzed.On this basis,the Cartesian plane is divided into operating,uncertainty,and restraining zones.Further,the operating and restraining trajectory indices are meticu-lously designed and a protection criterion based on these indices is formed to accurately separate internal faults from other events,unaffected by CT saturation,errors,and outliers.The exceptional performance of the proposed protection method is extensively validated through PSCAD simulations and a hard-ware-in-the-loop testing platform.Regarding the dependability,sensitivity,and security,the proposed protection method outper-forms three state-of-the-art differential protection methods.

Associations of prenatal exposure to bisphenols with BMI growth trajectories in offspring within the first two years:evidence from a birth cohort study in China

Background Prenatal bisphenol exposure has been reported to be associated with lower birth weight and obesity-related indicators in early childhood.These findings warrant an investigation of the relationship between prenatal bisphenol exposure and the dynamic growth of offspring.This study aimed to evaluate the relationship of maternal bisphenol concentration in urine with the body mass index(BMI)growth trajectory of children aged up to two years and to identify the critical exposure periods.Methods A total of 826 mother–offspring pairs were recruited from Wuhan Children’s Hospital between November 2013 and March 2015.Maternal urine samples collected during the first,second,and third trimesters were analyzed for bisphenol A(BPA),bisphenol S,and bisphenol F(BPF)concentrations.Measurements of length and weight were taken at 0,1,3,6,8,12,18,and 24 months.Children's BMI was standardized using the World Health Organization reference,and group-based trajectory modeling was used to identify BMI growth trajectories.The associations between prenatal bisphenol exposure and BMI growth trajectory patterns were assessed using multinomial logistic regression models.Results The BMI growth trajectories of the 826 children were categorized into four patterns:low-stable(n=134,16.2%),low-increasing(n=142,17.2%),moderate-stable(n=350,42.4%),and moderate-increasing(n=200,24.2%).After adjusting for potential confounders,we observed that prenatal exposure to BPA during the second trimester[odds ratio(OR)=2.20,95%confidence interval(CI)=1.09–4.43]and BPF during the third trimester(OR=3.28,95%CI=1.55–6.95)at the highest quartile concentration were associated with an increased likelihood of the low-increasing BMI trajectory.Furthermore,in the subgroup analysis by infant sex,the positive association between the highest quartile of prenatal average urinary BPF concentration during the whole pregnancy and the low-increasing BMI trajectory was found only in girls(OR=2.82,95%CI=1.04–7.68).Conclusion Our study findings suggest that prenatal exposure to BPA and BPF(a commonly used substitute for BPA)is associated with BMI growth trajectories in offspring during the first two years,increasing the likelihood of the low-increasing pattern.